Coal-sizing screen



Feb. 9, 1960 B. F. HENDRICKSON COAL-SIZING SCREEN Filed Nov. '7, 1956 F/ 6 QUARTER OF AN INCH SIDE PLAY Y PER FOOT OF WIDTH QUARTER OF AN INCH SIDE PLAY PER FOOT OF WIDTH INVENTOR United States PatentO COAL-SIZING SCREEN Ben F. Hendrickson, Pound, Va.

Application November 7, 1956, Serial No. 620,863

Claims. (Cl. 209-393) This invention relates to vibrator screens and has for its principalobject the provision of a sturdy screen capable of great animation and free of tendency to blind or blank out when screening masses of wet material.

An important feature of the invention is the provision of a light weight screen particularly suited to vibrator use in connection with the making ready for commercial use of all grades of coal and especially wet bituminous coal handled in quantities up to and exceeding ten thousand tons per day per screen.

A further object of the invention is to provide a screen which can be put into use and then forgotten as far as maintenance is concerned for it has no parts which come in contact with the coal or other material to be screened which could get out of shape or become useless by reason of breakage, the coal coming in contact with no part which is bolted, Welded or rigidly secured.

The best screens now obtainable for use with present day coal preparation methods, while quite sturdy, are of such weight that the vibrator must operate at a slower rate than is desired. The heavy weight of such coal sizing screens also tends to shorten appreciably the life of the screen, the normal period of use being about three months. By using sturdy round tie rods which do not come in contact with the material being screened and mounting links of round wire on these tie rods the total weight is reduced to such an extent that the vibrator may operate at a fast rate of speed, the rigid screen frame of transverse tie rods and longitudinal steel bars may be provided with a shock absorber cushion of simple design, the area through which the material may pass is increased from 30% to 40%, and the useful life of the screen is increased manyfold. Obviously the screening spaces may be made to suit any circumstances by merely substituting a different diameter of wire stock material from which to form the links, or by the use of washers between the looped ends of the links, or both.

In the drawings:

Figure 1 is a plan view.

Figure 2 is an end elevation.

Figure 3 is a central longitudinal section.

The screen consists primarily of a sturdy rigid frame, shock absorbing means conveniently side members of the screen and made of elongated rubber strips, and the links which are the only members of the screen which come in contact with the material to be screened.

The preferred form of the screen is one using solid stainless steel half-inch tie rods 10, each welded to two steel spacer bars 11 so as to form what is substantially an integral frame having such movement in the rubber side members 14 as to give a shock absorber effect when the screen is agitated in any of the usual manners.

A preferred method of securing the spacer bars 11 to the transverse tie rods 10 is by forming holes 15 in the spacer bar of such size as to snugly fit the tie rods, then to countersink these holes as at 16 and finally to weld the tie rods to the spacer bars at each side as by adjacent links.

welds 17 spaced appreciably inward from the ends of the tie rods. The countersinking is of great advantage as the spacer bars 11 may then quite snugly fit the sides of the rubber cushioning members 14.

The side members 14 are of-a heavy grade of solid rubber stock having alined holes 20 to receive the ends of the tie rods 10 as they extend beyond the spacer bars 11 on both sides. While I prefer the ends of the tie rods 10 to extend flush with the outside face 21 of the side cushioning members 14, they may extend a trifle short of or a trifle beyond this rubber side strip for the cushioning members 14 are engaged by the vibrator (not shown) only at top and bottom 22 and 23 respectively by the rails of the vibrator.

The links, generally numbered 30, are of round wire of such diameter as to afford thedesired spacing between As a typical example, for a screen roughly three feet by four feet the tie rods are solid steel a half inch in diameter, the links are of one-eighth inch stainless steel round wire, and the longitudinally extending rubber side members are four feet long and square in cross section, an inch on the side.

The tie rods are two and a half inches between centers for this size of screen and since the links are in fairly close contact, the space between the links is about their own diameters if no washers are used on the center tie rods, except that to provide the necessary side to side movement of the links a quarter of an inch is provided for each foot of width of the screen so that in six inches of width there will be twenty-three links extending either to the right or left of any one center tie bar and twenty-two links extending in the other direction,

assuming an eighth inch diameter link stock.

The links for a 2 /2" spacing and a bent link of such stainless wire stock'would be about 3%" long overall. Each link is loosely looped as at 31 around two adjacent 1 stainless steel tie rods, the diameter of the loop being for a half inch diameter rod. The ends 33 of the link preferably clear the top of the link by about no degree of accuracy being necessary because each end 33 is immediately below the fiat top of its link and therefore affording no obstruction to the passage of coal between adjacent links.

' In order to maintain the end links parallel, I space adjacent loops 31 on the end tie rods by a plurality, shown as three but preferably four, of washers 40. These, like other metal parts of the screen preferably are of an excellent grade of stainless .steel, a convenient gage being .031" for an eighth inch round wire stock of the links. Obviously, a slight increase in" screening area is obtained by using five of the washers 40 between each loop on the end bar and by adding an additional washer per intermediate link on each of the many transverse.

the vibrator has a circular motion without any lateral reciprocation. The many links 30 are constantly in motion and the animation may correctly be. described as a dancing motion of the links as they rise and fall on the tie rods 10 and in so doing. necessarily tilt through the slight angle that is permitted by the small but essential clearance which is provided. Because of the relatively slight weight of the screen, the vibrator can move at a desirable high speed. The rubber side members act as shock absorbers for the rigid frame of the screen as each transverse tie rod end fits snugly in its own hole in the two resilient side members and there is no other con- 3 nection between the rods and the rubber. While theends of the loops of the links may be closed just enough to prevent them from coming off the tie rods, it is best to make the gap only abit greaterthanthe diameterof-iithef link as this will allow ample movement of the-links: up 3 and down on thetie rods. Direct side to side-fmovement of the links, however; is much more limited asea'ch looped end closely engagesanadjacent linkon both sides at each center tie rod or by washersif the space is: in

creased by such means: As the "vibratorstarts' its rapid motion, the links begin their many cycles of movement, both up and down, forward and backward, and tea certain degree also from sideto side;

permit the material to screen through from any direc tion and at any pressure within reason. Screens of this type which have beenin use for much over half a year are still in use, showing'no signs of wear orpossibility of breakage. This seems to be due in large part to the total absence of welded connections between the links and the tie rods.

What I claim is:

1. A screen for vibrator use in sizing bituminous coal comprising a frame of a pair of longitudinal members and a number exceeding three of parallel transverse members rigidly secured to the longitudinal members, shock absorber means for the frame, and a plurality of rigid links joining adjacent transverse members, said links being spaced from each other and extending loosely around the transverse members so as to have freedom of movement up and down, transversely, and longitudinally of the frame,

2. The device ofclaim 1 in which the transverse mem 4. The screen of claim 1 in which the transverse members are cylindrical tie rods and the links are of round wire having two looped ends, one surrounding each proximate transverse tie rod, the inner diameter of each loop being roughly 1 and ,4 times the diameter of the rod.

5. The screen of claim 1 in which the transverse members are secured to the longitudinal members in substantially integral fashion and extend into and are imbedded in resilient side members forming the shock absorber means.

6. The screen of'claim 1 in which the transverse members are round tie rods, the longitudinal members are steel bars welded to the transverse tie rods and the shock absorber means are two' rubber side members square in cross section and having holes therein to receive the ends of the transverse tie rod members and completely enclose same.

7. A light weight boltless screen for vibrator use in sizing bituminous. coal. comprising a pair of parallel resilient rubber side members square in cross section, each having a series of. alined cylindrical holes" therein, a flat spacer bar adjacent 'each side member and having countersunk holes alined with the holes in the side members with the larger diameter of' the countersink on the side en.- gaging the side member, a series of round tie rods extending through alined holes and welded to both spacer bars on the face engaging the proximate side member,

The'loosenessof the links and their movements in so many directions readily and round wirevlinks each having oppositely curved loops.

at the two ends to surround two adjacent tie rods, with freedom to move up and down a distance roughly equal to A of the diameter of the tie rod, and washers mounted on the round tie rods between the loops of the links on the end tie rods to hold alternate links generally parallel to the side members but with sufficient looseness to permit each individual link to tilt on adjacent rods and 'ameter of said holes, welding material filling the space of links of round steel wire of about one-fourth of the t around the rods in tliecountersunk holes, with a series diameter of the round rods, said links being looped at each end to embrace two adjacent transverse round rods with suificient play to leave freedom to move up and 1 down, transversely and longitudinally of the frame, and

therefore having dancing movement when the screen is given'the usual vibrator action.

9. The combination of claim 8- in which the bars, the

rods, and the links are of stainless steel, the spacing of i the links on the transverseround rods is such as to make the direct side-to-side movement of a link relatively:

slight by providing an excess transverse width between the parallel steel bars of about a quarter-inchper foot ofwidth of the screen-and the size of the loops is such asito make theup and down movement greater than the side-to-side movement.

10. A lightweight, sturdy screen for vibrator use in sizing wet bituminous coal com-prising a pair of parallel one-piece resilient rubber side members each having a seriesof alined cylindrical holes therein, a spacer bar engaging each side member and having countersunk holes alined with the holes in the side members with the larger diameter of the countersink on the side engaging the side members, a series ofround tie rods extending through the alined holes and fitting snugly the smaller diameterl of such holes, welded to both spacer bars in the space in each countersunk hole surrounding the round rod, and roundv wire links each having oppositely curved loops to surround two adjacent tie rods with freedom to move up and down, and washers holding all of the links parallel to the two side members with sufficient-looseness to permit each individual link to tilt on adjacent rods and tot move away from the tie rods at either or both ends of the link.

References Citedin the file of this patent UNITED STATES PATENTS 327,050 Wulfert Sept. 29, 1885 419,907 Armstrong et a1. Jan. 21, 1890 1,260,409 Lieberman Mar. 26, 1918 1,314,194 Hoover .Aug. 26, 1919 1,961,534 Symons June 5, 1934: 2,080,884 Anderson May 18, 1937 2,362,099 Sargent Nov. 7, 1944 2,690,265 Bixby Sept. 28, 1954 FOREIGN PATENTS 303,970 Great Britain Jan. 17, 1929 317,326 Germany Dec. 18, 1919 691,617 Great Britain May 20, 1953' 

